ISTANBUL -- Turkey's unexpected move to launch raids against Kurdish rebels at the same time it is cracking down on the Islamic State group risks ending a period of relative calm that has been a boon for Turkey's democracy and economy.

The peace process launched in 2012 with the Kurdistan Workers' Party, or PKK, has been one of the signature achievements of President Recep Tayyip Erdogan, ending decades of violence that has left thousands dead. But that came to a sudden end in recent days as the Kurdish rebel group claimed responsibility for the killing of two Turkish policemen, and Turkish jets slammed a Kurdish stronghold in northern Iraq.

Turkish officials have portrayed the airstrikes in Iraq against the Kurds, and in Syria against IS, as a decisive move to protect Turkish democracy against terrorism and to change an unfavourable dynamic in its backyard. They say that the move against the PKK was a necessary response to recent acts of violence. Prime Minister Ahmet Davutoglu also accused the Kurdish rebel group, which Turkey and the U.S. consider a terrorist group, of not keeping a pledge to withdraw armed fighters from Turkish territory and to disarm.

But hitting the PKK's mountainous stronghold in Qandil, Iraq, in two bombing runs was an escalation that could make it hard to put the peace process back together again. Already, the PKK has declared the end of a cease-fire.

The developments follow major political gains for Turkish Kurds, whose main political party, the HDP, for the first time cleared a 10-per cent threshold for entering parliament in June elections. The election of 80 Kurdish members of parliament from HDP upended Turkish politics by ending the ruling majority of Erdogan's Justice and Development Party, or AKP. Kurdish leaders say Erdogan's camp secretly wants coalition talks between AKP and other parties to fail so that the longtime ruling party can try again to reach a majority in repeat elections that could come as early as November.

"At the moment, the acting prime minister is, step by step, taking Turkey toward a war," HDP co-chair Selahattin Demirtas said of Davutoglu, adding that the bombings across Turkey's border "are all part of the government plan to save themselves."

Turkey could now face a return to a guerrilla war with the PKK that only months ago looked likely to end for good in a peace agreement -- even as IS is destabilizing Turkey with the threat of further violence.

"The fact that Turkey is now clamping down on IS, which is liable to retaliate and at the same time taking on the PKK, raises great uncertainty for Turkey," said Bulent Aliriza, director of the Turkey Project at the Center for Strategic and International Studies in Washington.

The past week of worrying news in Turkey has included a suicide bombing, an IS ambush of Turkish soldiers along the border, PKK reprisals and the arrest of hundreds across Turkey accused of affiliations with IS, the PKK and a leftist extremist group. These security problems have also raised concern about the Turkish economy, which just in this brief spurt of turmoil has seen the Turkish lira fall by about 4 per cent.

Turkey's move against IS in the wake of last week's suicide bombing in southeast Turkey, as well as the opening of air bases for U.S. operations against the extremist group, was broadly welcomed by the U.S. and other NATO allies, who have long pressured Ankara to take more decisive action. But the allies have raised concern about the attack on the PKK.

Brett McGurk, a U.S. deputy special presidential envoy for the global coalition to counter the Islamic State, seemed to distance the U.S. from the strike on the Kurds, commenting on Twitter over the weekend that there was no connection between the attack and a recent agreement with Turkey to intensify co-operation against IS. He also urged both Turkey and the PKK to de-escalate tensions, a message echoed by other allies.

Dogu Ergil, a columnist for Zaman newspaper and lecturer at Istanbul Fatih University, said that the Turkish government may have taken an opportunistic hit at the PKK, using Western support of the moves against IS to lessen the criticism: "To attack the Kurds all of a sudden would have been problematic from the point of view of international legitimacy."

He added that the AKP may hope to return to peace negotiations from a position of strength following elections.

"But this isn't a tap that you can turn on and off," he said. "There are feelings involved. You cannot snuggle up again as if nothing has happened."